The word is out: 'Criminal Minds' is set to go out with a bang after its 15th season has just been announced. The show celebrated its impressive 300th episode in the fall of last year. However, it's certainly not the only series out there that has been on the air for an impressively long time.

Click through this gallery to see the world's longest-running TV shows.

'The Big Bang Theory' - The show, which follows the lives of theoretical physicist Dr. Sheldon Cooper and his quirky group of friends, will have performed an outstanding 12-season run by the time it ends in 2019.

'Law & Order' - Before making a name for himself as Mr. Big on 'Sex and The City,' Chris Noth played detective Mike Logan. His character even made a return to the screen in 'Law & Order: Criminal Intent.'

'Sesame Street' - 'Sesame Street' wins the prize for the series that has been on air the longest, with an impressive 48 seasons. The kids show, which first aired in 1969, features more than 4,400 episodes.

'The Simpsons' - When 'The Simpsons' first aired over three decades ago, no one could have imagined that the yellow family of five would have such a huge impact on American TV. Today, Homer, Marge, Bart, Lisa, and Maggie are still going strong, and are in the midst of their 30th season!

'Doctor Who' - The series was first released in 1963, and has been on the air for 37 seasons. In 2018, the cult show entered a new era with the role of the doctor being played by a woman, Jodie Whittaker, for the very first time.

'ER' - On air from 1994 to 2009, the series starred none other than Hollywood giant George Clooney, as well as Julianna Margulies and Noah Wyle, who later went on to appear in 'The Good Wife' and 'Falling Skies,' respectively.

'The Tonight Show' - 'The Tonight Show' is the longest-standing talk show on television, and it was one of the first late-night talk shows to be broadcast when it aired back in 1957. Johnny Carson was the longest-serving host, for 30 seasons.

'Scooby-Doo' - Even though it's been airing in different networks since it first premiered, Scooby-Doo as a cartoon has graced our screens since 1969. Everyone's favorite "meddling dog" became a staple in many people's childhood.

'Grange Hill' - The British TV series, which followed the story of life in a comprehensive school, finally ended in 2008 after running for 31 seasons and airing 601 episodes. It won the BAFTA for Best Children's Programme four times: in 1979, 1980, 1986, and 2001.

'Top Gear' - ‘Top Gear’ kicked off in 1977 and it lasted until 2001, when it was cancelled, only to be rebooted one year later. Its most famous hosts were trio Jeremy Clarkson, James May, and Richard Hamilton.

'Top Gear' - After a series of scandals that saw the departure of Clarkson, May, and Hamilton, the show returned in 2016 with hosts Chris Harris (right) and 'Friends' star Matt LeBlanc. However, Matt LeBlanc will be stepping down, to be replaced by Paddy McGuinness (middle) and Andrew Flintoff (left) for the 27th season.

Air-time legends: the longest-running TV series ever

'Criminal Minds' will end an epic run with its 15th season

The word is out: 'Criminal Minds' is set to go out with a bang after its 15th season has just been announced. The show celebrated its impressive 300th episode in the fall of last year. However, it's certainly not the only series out there that has been on the air for an impressively long time.

Click through this gallery to see the world's longest-running TV shows.